The good news is Twitch is moving to using HTML5 for the video part of player (already had HTML5 for chat and controls for over a year now) soon as they are currently in Beta testing. https://blog.twitch.tv/html5-beta-access-expands-99554ea982e4#.kgonqf5ek and https://help.twitch.tv/customer/portal/articles/2477288

The Flash Player embed is being depreciated as of Aug 29. https://blog.twitch.tv/flash-player-embed-deprecation-73a5df60f0df#.k1udqd8eh

You can try to view streams with the html5 player with say http://player.twitch.tv/?channel=channelnamehere&html5 (replace channelnamehere with channel) however there is no chat so you would have to say open a normal twitch stream and have chat change to a popout for example.

Also on Linux you should consider trying the livestreamer and its twitch gui. You do not need to login on livestreamer, just use it to search for channel and open stream (set stream type to hls in livestreamer gui) to send html5 streams to a media player like MPV. I do this on Linux and it uses a Lot less cpu usage especially if viewing Source in full screen. If you want chat you can got to stream in browser and open chat in a popout and MPV can be sized to whatever you want.

James, thank you for information but.. i really want to watch from browser and with chat in single window. only firefox has problems at least in ubuntu so no way to do something?

It works for me with the Flash Player 11.2.x and chat in browser but not really a fan of the cpu usage. Note unpartnered streamers do not have quality options like low, med, high, source unless number of viewers get high enough for quality trans-coding to kick in (maybe) and the odd streamer may require to viewers to sub in order to get say high/source.